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Country Boy

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  1. I am not sure why you say that collisions "create thrust". Such an engine or even a standard rocket creates thrust even in empty space where there are no air molecules to "collide" with.
  2. Density is "mass divided by volume", d= m/v, so dv= m and v= m/d. That is, volume is mass divided by density. We are told that the mass is 1.899x 10^{27} kg and the density is 1.24 x 10^3 kg per cubic m and we need to divide 1.899/1.24 kg(kg/m^3). Since dividing by a fraction you "invert and multiply" the units are kg(m^3/kg). The "kg" cancel leaving "m^3", cubic meters, as it should be for volume. You also have the numerical division wrong.
  3. "sqrt(1)" does not have any "solutions" because it is not a problem to be solved! The equation $x^2= 1$ has two solutions, x= 1 and x= -1. By definition, $\sqrt{y}$ is the positive number, x, such that $x^2= y$.
  4. In general, [tex]x^2= a^2[/tex] has two solutions, x= a and x=-a. But if [tex]x= \sqrt{a^2}[/tex] then x= |a|. In particular, there is NO x such that [tex]\sqrt{x}= -1[/tex].
  5. Okay, since your are talking about DC current where do "electromagnetic waves" come into it? Electromagnetic waves do not travel along wires.
  6. v apparently is a function of [tex]\rho[/tex] and [tex]\rho[/tex] is a function of both x and t so what does v' mean? Is it a derivative? With respect to x or v?
  7. What kind of help do you want? Unless you are expecting someone to do it for you, you should tell us what you have already done, what basic concepts you are using, how you will be drawing the lines, etc.
  8. I don't see that as particularly hard to differentiate. It is basically a= b(1- cxy)^2+ cx^2. The derivative is given by 0= 2b(1- xy)(-xy'- y)+ 2cx. Solving for y', -xy'- y= -cx/(b(1-xy)), xy'= cx/(b(1- xy)- y, y'= c/(b(1- xy))- y/x. That will be 0 when c/(b(1- xy)= y/x, cx= by(1- xy)).
  9. No. [tex]0*\infty[/tex] is NOT 0, it is "undefined". [tex]\frac{\pi}{\infty}*\infty[/tex] is "undefined".
  10. Joigus: "CuriosOne, I've never seen anyone who understands so little and claims to understand so much at the same time. I'm very nearly done with you too." That's why I have come to the conclusion that CuriosOne does understand all of this and just thinks it is funny to pretend to be stupid!
  11. I assume you have already had the exam. But first, what is "the first law of Mendel"?
  12. Your title is confusing. Saying "life didn't start on Earth" is not the same as saying "life didn't only start on earth"!
  13. When I first saw "Earth's satellite and its first space speed" I immediately assume that the "Earth's satellite" referred to the moon! Then I opened it and saw "the artificial satellite" my first thought was "the"? There are many satellites- "an artificial satellite". In any case, you can calculate the speed at which any satellite, at a given height,, must travel to maintain that height. And a "geosynchronous" satellite must travel at a speed that completes a full orbit (circle) in 24 hours.
  14. You have two different ranking methods with rank A and B in different orders. To be able to determine an order for A and B you will have to decide on how to weight the two methods. That will depend on which you think is more "accurate". For example if you think method 1 is twice as accurate as method 2, you would give 1 a weight of 2/3 and 2 a weight of 1/3 (because 2/3 is twice 1/3 and they add to 1). So you would rank A as (2/3)(.7)+ (1/3)(.5)= 19/3 and would rank B as (1/3)(.5)+ (1/3)(.7)= 12/3. A is ranked higher than B. But if you thought 2 was 50% more accurate than 1 you would giv
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